JP2018036115A - Attitude detection system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an attitude detection system for a vehicle for detecting the attitude of a vehicle with respect to the road surface.SOLUTION: An attitude detection system 1 for a vehicle for detecting the attitude of a vehicle 5 travelling on a road surface 100S on which magnetic markers 10 are laid includes: lateral deviation measuring means for measuring the lateral deviation with respect to each magnetic marker 10; and lateral deviation differentiating means for determining the difference between the lateral deviations from any one magnetic marker 10 that are measured by a plurality of lateral deviation measuring means 11 located at at least two positions separate from each other in the front and back direction of the vehicle 5.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an attitude detection system for detecting the attitude of a running vehicle.

  Conventionally, various control techniques have been proposed in order to stabilize the running of a vehicle (see, for example, Patent Document 1 below). In such a control technique, it is essential for better vehicle control to detect the posture of the vehicle while traveling and to grasp the traveling state with high accuracy. Various sensors, such as a yaw rate sensor and an acceleration sensor, are used to detect the posture of a running vehicle.

JP 2006-117176 A

  A sensor such as a yaw rate sensor or an acceleration sensor can only identify the relative attitude change of the vehicle by measuring the force acting on the sensor, and it is difficult to grasp the attitude of the vehicle with respect to the road surface. is there.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a vehicle attitude detection system that detects the attitude of a vehicle with respect to a road surface.

The present invention is a vehicle attitude detection system for detecting the attitude of a vehicle traveling on a road surface on which a magnetic marker is laid,
Lateral deviation amount measuring means for measuring the lateral deviation amount with respect to the magnetic marker;
A posture detection system for a vehicle, comprising: a lateral deviation amount difference unit that obtains a difference between lateral deviation amounts measured by any one of a plurality of lateral deviation amount measurement units located at at least two locations separated in the longitudinal direction of the vehicle. (Claim 1).

  The posture detection system for a vehicle according to the present invention is a device that detects the posture of a vehicle using a magnetic marker laid on a road surface. This posture detection system uses a plurality of lateral deviation amount measuring means spaced apart in the front-rear direction of the vehicle, and measures lateral deviation amounts for the same magnetic marker. Then, as an index representing the posture of the vehicle, a difference between the lateral deviation amounts measured by the lateral deviation amount measuring means having different positions in the longitudinal direction of the vehicle is obtained.

  As described above, according to the posture detection system of the present invention, the posture of the vehicle with respect to the road surface can be detected using the magnetic marker.

The front view which anticipates the vehicle which comprises the attitude | position detection system in Example 1. FIG. 1 is a configuration diagram of a posture detection system in Embodiment 1. FIG. 1 is a block diagram showing an electrical configuration of an in-vehicle device that constitutes a posture detection system in Embodiment 1. FIG. FIG. 3 is a block diagram illustrating a configuration of a magnetic sensor in the first embodiment. FIG. 3 is an explanatory diagram illustrating temporal changes in the magnetic distribution in the vehicle width direction when passing through a magnetic marker in the first embodiment. FIG. 3 is an explanatory diagram illustrating a temporal change in a peak value of a magnetic measurement value when passing through a magnetic marker in the first embodiment. FIG. 3 is an explanatory diagram of a lateral deviation amount measuring method according to the first embodiment. FIG. 3 is a flowchart showing the flow of processing by the posture detection system in the first embodiment. Explanatory drawing of the detection period by the back side sensor unit in Example 1. FIG. FIG. 3 is a flowchart showing a flow of vehicle posture detection processing in the first embodiment. FIG. 3 is an explanatory diagram of a lateral deviation amount by a front sensor unit and a lateral deviation amount by a rear sensor unit in the first embodiment. Explanatory drawing of difference Ofd of lateral deviation amount by the sensor unit of the front and back, and vehicle body deviation angle Af in Example 1. FIG. Explanatory drawing of the driving | running | working condition of neutral steer in Example 1. FIG. Explanatory drawing of the driving | running | working condition of an oversteer in Example 1. FIG. Explanatory drawing of the driving condition of understeer in Example 1. FIG. Explanatory drawing of the condition where a vehicle drive | works along the traveling path where the magnetic marker was laid in Example 2. FIG. Explanatory drawing of the relationship between the path | route direction of a traveling path, and the steering direction of a vehicle in Example 2. FIG.

A preferred embodiment of the present invention will be described.
It is preferable to provide posture angle detection means for acquiring an angle in the turning direction of the vehicle corresponding to the difference in the lateral deviation amount.
Differences in lateral deviation amounts measured for the same magnetic marker by a plurality of lateral deviation amount measuring means having different positions in the front-rear direction of the vehicle can be handled as an index representing the vehicle posture. However, the difference between the lateral deviation amounts is affected by the distance in the front-rear direction of the corresponding lateral deviation amount measuring means, and the value increases as the distance increases. On the other hand, the angle in the turning direction is a normalized index that is irrelevant to the length of the distance in the front-rear direction of the two lateral deviation measuring units.

It is preferable to detect the posture when the difference between the lateral deviation amounts measured by any one of the lateral deviation amount measuring means is less than a predetermined threshold for two magnetic markers that are located apart in the path direction of the travel path. ).
As a traveling situation that does not follow the route direction of the traveling path, a situation such as a lane change can be assumed. Thus, in a traveling situation that does not follow the route direction of the traveling path and involves a change in the course of the vehicle, the difference (absolute value) of the lateral deviation amounts measured for the same magnetic marker by the plurality of lateral deviation amount measuring means is the vehicle posture. Regardless, it can grow. If threshold determination is performed on the difference between the lateral deviation amounts measured by the same lateral deviation amount measuring means for the two magnetic markers, it is possible to determine with high accuracy whether or not the traveling situation is along the route direction of the traveling path. If detection of the vehicle posture is executed in a traveling situation along the route direction of the traveling path, high detection accuracy can be ensured.

A means for measuring a steering angle, which is a steering direction of a steering wheel provided in the vehicle, may be provided, and posture detection may be executed when the amount of change in the steering angle per unit time is less than a predetermined threshold.
In a traveling situation in which the steered wheels are steered suddenly, the difference (absolute value) of the lateral deviation amounts measured for the same magnetic marker by the plurality of lateral deviation amount measuring means may become large regardless of the vehicle posture. Thus, if the posture detection is executed when the amount of change in the steering angle per unit time is less than a predetermined threshold, the detection accuracy can be easily ensured.

It is preferable to detect the posture when the amount of change in the traveling direction of the vehicle per unit time is less than a predetermined threshold (Claim 5).
In a driving situation in which the traveling direction of the vehicle fluctuates abruptly, the difference (absolute value) of the lateral deviation amounts measured for the same magnetic marker by the plurality of lateral deviation amount measuring means may become large. Attitude detection is not appropriate. Therefore, it is preferable to detect the posture when the amount of change in the traveling direction of the vehicle per unit time is less than a predetermined threshold.

  Means for acquiring route data representing the route direction of the traveling road, means for measuring a steering angle which is a steering direction of a steering wheel provided in the vehicle, and a steering direction corresponding to the measured value of the route direction and the steering angle represented by the route data; Means for calculating the degree of coincidence, and posture detection may be executed when the degree of coincidence is equal to or greater than a predetermined threshold.

  When the degree of coincidence between the route direction of the travel path and the steering direction is greater than or equal to a predetermined threshold, it is determined that the travel situation is along the travel path, and the posture is detected. The degree of coincidence between the route direction and the steering direction is, for example, the reciprocal of the deviation between the position 100 m ahead in the route direction and the position 100 m ahead in the steering direction, or the phase between the curve represented by the route direction and the curve represented by the steering direction. The number of relationships can be adopted.

The embodiment of the present invention will be specifically described with reference to the following examples.
Example 1
This example is an example related to the attitude detection system 1 for detecting the attitude of the vehicle (vehicle attitude) using the magnetic marker 10 laid on the road surface. This will be described with reference to FIGS.

  The posture detection system 1 is a vehicle system for detecting a vehicle posture using a magnetic marker 10 laid on a road surface 100S as shown in FIGS. The posture detection system 1 includes an in-vehicle device including a combination of front and rear sensor units 11 including a magnetic sensor Cn (n is an integer of 1 to 15) and a control unit 12 that controls the sensor unit 11. It is configured. Hereinafter, after outline of the magnetic marker 10 constituting the posture detection system 1, the configuration of the in-vehicle device including the sensor unit 11 and the control unit 12 will be described.

As shown in FIGS. 1 and 2, the magnetic marker 10 is a road marker laid along the center of the lane 100 in which the vehicle 5 travels. The magnetic marker 10 has a columnar shape with a diameter of 20 mm and a height of 28 mm, and can be accommodated in a hole provided in the road surface 100S. The magnet constituting the magnetic marker 10 is a ferrite plastic magnet in which magnetic powder of iron oxide, which is a magnetic material, is dispersed in a polymer material, which is a base material, and has a characteristic of maximum energy product (BHmax) = 6.4 kJ / m ^3. It has. The magnetic marker 10 is laid while being accommodated in a hole formed in the road surface 100S.

この磁気マーカ１０は、磁気センサＣｎの取付け高さとして想定する範囲１００〜２５０ｍｍの上限の２５０ｍｍ高さにおいて、８μＴ（８×１０^−６Ｔ）の磁束密度の磁気を作用できる。 A part of the specification of the magnetic marker 10 of this example is shown in Table 1.

The magnetic marker 10 can act with a magnetism having a magnetic flux density of 8 μT (8 × 10 ⁻⁶ T) at an upper limit of 250 mm, which is an upper limit of a range of 100 to 250 mm assumed as a mounting height of the magnetic sensor Cn.

Next, the sensor unit 11 and the control unit 12 constituting the attitude detection system 1 will be described.
As shown in FIGS. 1 and 2, the sensor unit 11 is a unit attached to a vehicle body floor 50 that hits the bottom surface of the vehicle 5. The sensor unit 11 is an example of a lateral deviation amount measuring means for measuring the lateral deviation amount of the vehicle 5 with respect to the magnetic marker 10. In the posture detection system 1, sensor units 11 are arranged at two positions that are spaced apart in the front-rear direction of the vehicle 5. In the following description, the interval between the front sensor unit 11 and the rear sensor unit 11 in the front-rear direction of the vehicle is referred to as a sensor span S.

The front sensor unit 11 is attached near the inside of the front bumper, and the rear sensor unit 11 is attached near the inside of the rear bumper. In the case of the vehicle 5 of this example, the mounting height with respect to the road surface 100S is 200 mm.
As shown in FIGS. 2 and 3, each sensor unit 11 includes 15 magnetic sensors Cn arranged in a straight line along the vehicle width direction, and a detection processing circuit 110 incorporating a CPU (not shown). Yes. Fifteen magnetic sensors Cn are arranged at equal intervals of 0.1 m, and the interval between the magnetic sensors at both ends is 1.4 m.

  The detection processing circuit 110 (FIG. 3) is an arithmetic circuit that executes various arithmetic processes such as a marker detection process for detecting the magnetic marker 10. The detection processing circuit 110 is configured by using an element such as a ROM (read only memory) or a RAM (random access memory), in addition to a CPU (central processing unit) that executes various operations. .

  The detection processing circuit 110 acquires a sensor signal output from each magnetic sensor Cn and executes marker detection processing and the like. All the detection results of the magnetic marker 10 calculated by the detection processing circuit 110 are input to the control unit 12. As a detection result, in addition to whether or not the magnetic marker 10 has been detected, there is a lateral shift amount with respect to the magnetic marker 10. Note that both the front and rear sensor units 11 can execute marker detection processing at a cycle of 3 kHz.

  Here, the configuration of the magnetic sensor Cn will be described. In this example, a one-chip MI sensor in which the MI element 21 and the drive circuit are integrated is employed as the magnetic sensor Cn (see FIG. 4). The MI element 21 is an element including an amorphous wire 211 made of a CoFeSiB alloy and having substantially zero magnetostriction, and a pickup coil 213 wound around the amorphous wire 211. The magnetic sensor Cn detects magnetism acting on the amorphous wire 211 by measuring a voltage generated in the pickup coil 213 when a pulse current is applied to the amorphous wire 211. The MI element 21 has detection sensitivity in the axial direction of the amorphous wire 211 that is a magnetic sensitive body. In each magnetic sensor Cn of the sensor unit 11 of this example, an amorphous wire 211 is disposed along the vertical direction.

  The drive circuit is an electronic circuit including a pulse circuit 23 that supplies a pulse current to the amorphous wire 211 and a signal processing circuit 25 that samples and outputs a voltage generated in the pickup coil 213 at a predetermined timing. The pulse circuit 23 is a circuit including a pulse generator 231 that generates a pulse signal that is a source of a pulse current. The signal processing circuit 25 is a circuit that takes out an induced voltage of the pickup coil 213 through a synchronous detection 251 that is opened and closed in conjunction with a pulse signal, and amplifies it with a predetermined amplification factor by an amplifier 253. The signal amplified by the signal processing circuit 25 is output to the outside as a sensor signal.

  The magnetic sensor Cn is a highly sensitive sensor having a magnetic flux density measurement range of ± 0.6 millitesla and a magnetic flux resolution within the measurement range of 0.02 microtesla. Such high sensitivity is realized by the MI element 21 utilizing the MI effect that the impedance of the amorphous wire 211 changes sensitively according to the external magnetic field. Further, the magnetic sensor Cn can perform high-speed sampling at a cycle of 3 kHz, and is compatible with high-speed driving of the vehicle. In this example, the period of the magnetic measurement by the magnetic sensor Cn is set to 3 kHz, and the magnetic sensor Cn inputs a sensor signal to the detection processing circuit 110 every time the magnetic measurement is performed.

Table 2 shows a part of the specifications of the magnetic sensor Cn.

As described above, the magnetic marker 10 can act with magnetism having a magnetic flux density of 8 μT (8 × 10 ⁻⁶ T) or more in the range of 100 to 250 mm assumed as the mounting height of the magnetic sensor Cn. If the magnetic marker 10 acts on magnetism having a magnetic flux density of 8 μT or more, it can be detected with high reliability using the magnetic sensor Cn having a magnetic flux resolution of 0.02 μT.

  Next, as shown in FIGS. 1 to 3, the control unit 12 is a unit that controls the front and rear sensor units 11 and detects the vehicle posture using the detection results of the sensor units 11. The detection result of the vehicle posture by the control unit 12 is input to a vehicle ECU (not shown), and is used for various vehicle controls for improving driving safety such as throttle control, brake control, and torque control of each wheel.

  The control unit 12 is a unit including an electronic board (not shown) on which a memory element such as a ROM or a RAM is mounted in addition to a CPU that executes various operations. The control unit 12 controls the operation of the front sensor unit 11 and the rear sensor unit 11 and detects the vehicle posture using the detection result of each sensor unit 11.

The control unit 12 has functions as the following means.
(A) Period setting means: when the front sensor unit 11 detects the magnetic marker 10, the time point when the rear sensor unit 11 can detect the same magnetic marker 10 is predicted, and the time period including the time point when the same can be detected Means for setting as a detection period
(B) Lateral deviation amount difference means: means for calculating the difference between the lateral deviation amount with respect to the magnetic marker 10 measured by the front sensor unit 11 and the lateral deviation amount measured by the rear sensor unit 11.
(C) Attitude angle detection means: means for detecting the vehicle attitude from the difference in lateral deviation between the front and rear sensor units 11. The contents of the detected vehicle posture will be described in detail later.

Next, (1) marker detection processing for each sensor unit 11 to detect the magnetic marker 10, (2) flow of overall operation of the posture detection system 1, and (3) vehicle posture detection processing will be described.
(1) Marker detection processing The front and rear sensor units 11 execute marker detection processing at a cycle of 3 kHz under the control of the control unit 12. The sensor unit 11 obtains a magnetic distribution in the vehicle width direction by sampling the magnetic measurement values represented by the sensor signals of the 15 magnetic sensors Cn at each execution period (p1 to p7) of the marker detection process (see FIG. 5). ). The peak value of the magnetic distribution in the vehicle width direction becomes maximum when passing through the magnetic marker 10 as shown in the figure (period p4 in FIG. 5).

  When the vehicle 5 travels along the lane 100 on which the magnetic marker 10 is laid, the peak value of the magnetic distribution in the vehicle width direction increases every time it passes through the magnetic marker 10 as shown in FIG. In the marker detection process, a threshold value determination regarding this peak value is executed, and it is determined that the magnetic marker 10 has been detected when it is equal to or greater than a predetermined threshold value.

  When detecting the magnetic marker 10, the sensor unit 11 specifies the position in the vehicle width direction of the peak value of the magnetic distribution in the vehicle width direction, which is the distribution of the magnetic measurement values of the magnetic sensor Cn. If the position of the peak value in the vehicle width direction is used, the lateral deviation amount of the vehicle 5 with respect to the magnetic marker 10 can be calculated. In the vehicle 5, the sensor unit 11 is attached so that the central magnetic sensor C 8 is positioned on the center line of the vehicle 5. Therefore, the deviation of the position in the vehicle width direction of the peak value with respect to the magnetic sensor C 8 is the magnetic marker 10. The amount of lateral displacement of the vehicle 5 with respect to

  In particular, as shown in FIG. 7, the sensor unit 11 of this example performs curve approximation (secondary approximation) on the magnetic distribution in the vehicle width direction, which is the distribution of magnetic measurement values of the magnetic sensor Cn, and the peak value of the approximate curve is obtained. The position in the vehicle width direction is specified. If the approximate curve is used, the position of the peak value can be specified with an accuracy finer than the interval between the 15 magnetic sensors, and the lateral deviation amount of the vehicle 5 with respect to the magnetic marker 10 can be measured with high accuracy.

(2) Overall Operation of Attitude Detection System 1 The overall operation of the attitude detection system 1 will be described with reference to the flowchart of FIG.
The control unit 12 causes the front sensor unit 11 to execute the marker detection process (S101, first detection step), and repeatedly executes the detection until the magnetic marker 10 is detected (S102: NO). When the control unit 12 receives an input indicating that the magnetic marker 10 has been detected from the front sensor unit 11 (S102: YES), the control unit 12 is a time period for causing the rear sensor unit 11 to execute marker detection processing. A period is set (S103, period setting step).

  Specifically, as shown in FIG. 9, the control unit 12 first calculates a required time δta obtained by dividing the sensor span S (m) by the vehicle speed (vehicle speed) V (m / second) measured by the vehicle speed sensor. The time t1, which is the time when the magnetic marker 10 is detected by the front sensor unit 11, is added. In this way, by adding the required time δta to the time t1, the time t2 when the rear sensor unit 11 can detect the magnetic marker 10 can be predicted. Then, the control unit 12 starts the time (t2−δtb) obtained by subtracting the section time δtb obtained by dividing the reference distance 1 (m) by the vehicle speed V (m / second) from the time t2, and uses the section time δtb as the time. A time interval in which the time (t2 + δtb) added to t2 ends is set as the detection period. The reference distance can be appropriately changed in consideration of the detection range of the sensor unit 11 and the like.

  The control unit 12 causes the rear sensor unit 11 to repeatedly execute marker detection processing within the detection period (FIG. 9) set in step S103 (S104: NO → S114, second detection step). The contents of this marker detection process are the same as the marker detection process by the front sensor unit 11 in step S101.

  If the control unit 12 can detect the magnetic marker 10 with the rear sensor unit 11 in the detection period (FIG. 9) (S104: YES → S105: YES), the vehicle attitude detection process described below for detecting the vehicle attitude is performed. Is executed (S106). On the other hand, if the magnetic sensor 10 can be detected by the front sensor unit 11 (S102: YES), but the magnetic marker 10 cannot be detected by the rear sensor unit 11 in the above detection period (FIG. 9). (S104: YES → S105: NO), the control unit 12 returns to the marker detection process (S101) by the front sensor unit 11 and repeats the above series of processes.

(3) Vehicle posture detection processing The vehicle posture detection processing (step S106 in FIG. 8) executed by the control unit 12 is a step of calculating the difference between the lateral deviation amounts measured by the front and rear sensor units 11 as shown in FIG. 10 (S201). And a step (S202) of calculating a vehicle body deviation angle representing a vehicle body displacement with respect to the traveling direction.

In step S201, as shown in FIG. 11, when the vehicle 5 passes the magnetic marker 10, the difference Ofd between the lateral deviation amount Of1 measured by the front sensor unit 11 and the lateral deviation amount Of2 measured by the rear sensor unit 11. (See FIG. 12) is calculated by the following equation.

In step S202, as shown in FIG. 12, a vehicle body deviation angle Af that is an angle formed by the traveling direction Dir of the vehicle 5 with respect to the vehicle axis Ax in the front-rear direction of the vehicle 5 is calculated. The vehicle body deviation angle Af is calculated by the following equation including the lateral deviation amount difference Ofd and the sensor span S.

  When the vehicle is traveling along a path with a constant curvature, including a straight path that can be grasped as a traveling path with an infinite curvature radius, the so-called inner ring difference is ideally compared to the trajectory of the front wheels. The locus of the rear wheel is on the inner circumference side by that amount. For example, when turning the corner of an intersection at a right angle, the difference between the inner wheels becomes obvious, but when traveling on a curve with a large radius of curvature such as on an expressway, the inner wheel difference can be ignored, so the trajectories of the front and rear wheels are almost the same. To do.

  While the vehicle 5 is traveling along a path of constant curvature, if a stable driving state of neutral steer where neither oversteering nor understeering occurs is realized, the front and rear sensor units The lateral deviation amount Of1 (refer to FIG. 12) measured by 11 and Of2 match, and the difference Ofd becomes almost zero. When the difference Ofd in the lateral deviation measured by the front and rear sensor units 11 becomes zero, the vehicle body deviation angle Af based on the difference Ofd becomes zero.

  When the vehicle is running on the right curve as shown in FIG. 13, the vehicle body deviation angle Af is zero and the vehicle is in the tangential direction of the arc forming the right curve under the stable driving condition in which neither oversteer nor understeer occurs. The axis Ax of the vehicle body coincides with the five traveling directions Dir. On the other hand, in the driving situation where the absolute value of the difference Ofd and the vehicle body deviation angle Af is large even though the vehicle 5 is traveling along a path of constant curvature, There is a possibility that understeering or oversteering has occurred due to slippage.

  For example, in a situation where the vehicle is traveling along a right curve traveling path, as shown in FIG. 14, if the vehicle body deviation angle Af with the clockwise direction being positive is larger than zero, the rear wheel may escape to the outside of the right curve, An oversteer situation is assumed where the front wheels are caught inside. Further, for example, in a situation where the vehicle is traveling along a right curve traveling path, as shown in FIG. 15, if the vehicle body deviation angle Af is a negative value smaller than zero, there is an understeer situation in which the front wheels escape to the outside of the left curve. is assumed.

  Thus, the vehicle body deviation angle Af is an index representing the angular deviation of the turning direction of the vehicle body direction with respect to the traveling direction Dir of the vehicle 5 and is normalized regardless of the magnitude of the sensor span S of the front and rear sensor units 11. It is an indicator.

  The lateral displacement amount difference Ofd (see FIG. 12) can also be used as an index representing the attitude of the vehicle 5. The situation where the difference Ofd in the lateral deviation measured by the front and rear sensor units 11 is zero is a traveling situation where the axis Ax of the vehicle body coincides with the traveling direction Dir of the vehicle 5, as shown in FIG. On the other hand, the situation where the absolute value of the lateral displacement difference Ofd is large is a traveling situation where the axis Ax of the vehicle body does not coincide with the traveling direction Dir of the vehicle 5, as shown in FIGS.

  As described above, the posture detection system 1 is a system that detects the vehicle posture using the magnetic marker 10 laid on the traveling road. According to this posture detection system 1, the vehicle posture with respect to the road surface can be detected with high reliability.

  The posture detection system 1 measures the amount of lateral deviation with respect to the magnetic marker 10 by using two sensor units 11 that are separated from each other in the front-rear direction of the vehicle 5, and obtains the difference Ofd. Although the lateral deviation amount difference Ofd can be used as an index representing the vehicle posture as it is, in this example, the vehicle body deviation angle Af corresponding to the lateral deviation amount difference Ofd is further calculated. The lateral deviation amount difference Ofd is an index that depends on the angle of the vehicle 5 in the turning direction and increases as the sensor span S increases. On the other hand, the vehicle body deviation angle Af is a normalized index that does not depend on the length of the sensor span S of the front and rear sensor units 11.

  In this example, the sensor units 11 are provided at two locations in the front-rear direction of the vehicle 5. Instead of this, the sensor units 11 may be provided at three or more locations in the front-rear direction of the vehicle 5. The vehicle posture may be detected by obtaining indices such as the difference Ofd and the vehicle body deviation angle Af for any two combinations having different positions in the front-rear direction.

  In the marker detection process by the front sensor unit 11 or the rear sensor unit 11, a difference in magnetic measurement value is calculated between the magnetic sensor of the front sensor unit 11 and the magnetic sensor of the rear sensor unit 11, and this It is also possible to detect the magnetic marker 10 using the calculated value. According to this difference calculation, a difference magnetic component obtained by subtracting the magnetic component detected by the front magnetic sensor from the magnetic component detected by the rear magnetic sensor can be generated, which is effective in suppressing common noise such as geomagnetism. . In the difference calculation, the difference may be obtained between magnetic sensors having the same position in the vehicle width direction.

In this example, the magnetic sensor Cn having sensitivity in the vertical direction is employed. However, a magnetic sensor having sensitivity in the traveling direction may be used, or a magnetic sensor having sensitivity in the vehicle width direction may be used. Further, for example, a magnetic sensor having sensitivity in the biaxial direction of the vehicle width direction and the traveling direction, the biaxial direction of the vehicle width direction and the vertical direction, or the biaxial direction of the traveling direction and the vertical direction may be employed. A magnetic sensor having sensitivity in the three axial directions of the vehicle width direction, the traveling direction, and the vertical direction may be employed. If a magnetic sensor having sensitivity in a plurality of axial directions is used, the magnetic action direction can be measured together with the magnitude of the magnetism, and a magnetic vector can be generated. It is also possible to distinguish between the magnetism of the magnetic marker 10 and the disturbance magnetism using the difference of the magnetic vectors and the rate of change in the traveling direction of the difference.
In this example, a magnetic marker of a ferrite plastic magnet is illustrated, but a magnetic marker of a ferrite rubber magnet may be used.

(Example 2)
In this example, based on the attitude detection system of the first embodiment, the detection accuracy of the vehicle attitude is improved by limiting the traveling state of the detection target. The contents will be described with reference to FIGS.

  When the traveling locus of the vehicle 5 is not a constant curvature and the magnetic marker 10 is located in the curvature variation section, there is a possibility that the difference Ofd is increased due to a difference in the amount of lateral deviation measured by the front and rear sensor units 11. There is. In such a situation, the lateral displacement amount difference Ofd measured by the front and rear sensor units 11 with respect to any one of the magnetic markers 10 and the vehicle body displacement angle Af may not accurately reflect the attitude of the vehicle 5. .

Therefore, in the posture detection system of this example, the vehicle posture is detected in the following traveling conditions (1) to (4), thereby ensuring the detection accuracy.
(1) A case where the difference between the lateral deviation amounts measured by any one of the sensor units 11 with respect to two magnetic markers 10 that are spaced apart in the route direction of the traveling path is less than a predetermined threshold.
In this case, it is considered that the vehicle 5 is traveling along a traveling path in which the magnetic marker 10 is laid along the path direction as shown in FIG. In general, connecting sections of curves having different curvatures on the road are designed so that the change in curvature is smooth. Therefore, if the vehicle 5 is traveling stably along the travel path, the difference in the amount of lateral deviation measured by the front and rear sensor units 11 for any one of the magnetic markers 10 may be excessive. Few. Such a tendency is particularly noticeable in the case of an expressway where the change in curvature is set very smoothly in the connecting section.

(2) When the change amount of the steering angle per unit time is less than a predetermined threshold on the premise that the vehicle 5 includes means such as a steering angle sensor that measures the steering angle that is the steering direction of the steered wheels. .
When the change amount of the steering angle per unit time, that is, the change speed of the steering angle is fast and exceeds a predetermined threshold value, the traveling direction of the vehicle 5 changes abruptly. In this way, if the magnetic marker 10 is positioned in a section where the traveling direction of the vehicle 5 changes suddenly, naturally, the difference between the lateral deviation amounts measured by the front and rear sensor units 11 for any one of the magnetic markers 10 is large. There is a possibility. In such a case, there is a high possibility that the attitude of the vehicle 5 cannot be detected with high accuracy due to the difference in the lateral displacement amount.

(3) When the amount of change in the traveling direction of the vehicle 5 per unit time is less than a predetermined threshold.
When the amount of change in the traveling direction of the vehicle 5 per unit time, that is, when the rate of change of the angle of the turning direction of the vehicle 5 is fast and is equal to or greater than a predetermined threshold, the sensor unit before and after the above (2) There is a high possibility that the attitude of the vehicle 5 cannot be detected with high accuracy due to the difference in the amount of lateral deviation measured by 11. Note that the change speed of the angle of the turning direction of the vehicle 5 may be measured by, for example, a yaw rate sensor, or may be measured from a change in the speed at which a distant view or a structure flows laterally in a continuous image captured by the front camera. .

(4) Corresponding to means for acquiring route data representing the route direction of the traveling road, means for measuring the steering angle that is the steering direction of the steering wheel provided in the vehicle 5, and corresponding to the measured values of the route direction and the steering angle represented by the route data When the degree of coincidence is equal to or greater than a predetermined threshold on the premise that the degree of coincidence with the steering direction is calculated.

  If the vehicle 5 is traveling along the traveling path, the attitude of the vehicle 5 can be detected with high accuracy using, as an index, the difference between the lateral deviation amounts measured by the front and rear sensor units 11 for any one of the magnetic markers 10. Is as in (1) above. When the degree of coincidence between the route direction and the steering direction is high, it can be determined that the vehicle 5 is traveling along the traveling path.

As the degree of coincidence between the route direction Dr and the steering direction Ds, for example, as shown in FIG. 17, the reciprocal of the deviation (distance) between the position 100 m ahead in the route direction Dr and the position 100 m ahead in the steering direction Ds is adopted. May be. Further, as shown in the figure, in a two-dimensional coordinate defined by the direction of the vehicle body axis Ax with the vehicle 5 as the origin and the vehicle width direction, a curve representing the route direction Dr and a curve representing the steering direction Ds are: You may employ | adopt a correlation coefficient as said matching degree. The route data can be acquired from map data used by a navigation system or an automatic driving system.
Other configurations and operational effects are the same as in the first embodiment.

  As described above, specific examples of the present invention have been described in detail as in the embodiments. However, these specific examples merely disclose an example of the technology included in the scope of claims. Needless to say, the scope of the claims should not be construed as limited by the configuration, numerical values, or the like of the specific examples. The scope of the claims includes techniques obtained by variously modifying, changing, or appropriately combining the above specific examples using known techniques and knowledge of those skilled in the art.

DESCRIPTION OF SYMBOLS 1 Posture detection system 10 Magnetic marker 100 Lane 100S Road surface 11 Sensor unit (lateral deviation measuring means)
110 detection processing circuit 12 control unit (period setting means, lateral deviation difference means, attitude angle detection means)
21 MI element 5 Vehicle

Claims (6)

An attitude detection system for a vehicle for detecting an attitude of a vehicle traveling on a road surface on which a magnetic marker is laid,
Lateral deviation amount measuring means for measuring the lateral deviation amount with respect to the magnetic marker;
A vehicle attitude detection system comprising: a lateral deviation amount difference unit that obtains a difference between lateral deviation amounts measured for any one magnetic marker by a plurality of lateral deviation amount measurement units located in at least two locations separated in the longitudinal direction of the vehicle.   The attitude detection system for a vehicle according to claim 1, further comprising attitude angle detection means for acquiring an angle in a turning direction of the vehicle corresponding to the difference in the lateral deviation amount.   3. The posture detection according to claim 1, wherein the difference between the lateral deviation amounts measured by any one of the lateral deviation amount measuring means is less than a predetermined threshold with respect to two magnetic markers positioned apart in the route direction of the travel path. An attitude detection system for a vehicle to be executed.   The vehicle according to any one of claims 1 to 3, further comprising means for measuring a steering angle that is a steering direction of a steered wheel provided in the vehicle, wherein the posture is changed when a change amount of the steering angle per unit time is less than a predetermined threshold value. An attitude detection system for a vehicle that performs detection.   The posture detection system for a vehicle according to any one of claims 1 to 4, wherein the posture detection is performed when the amount of change in the traveling direction of the vehicle per unit time is less than a predetermined threshold value.   The route direction represented by the route data represented by any one of claims 1 to 5, means for acquiring route data representing a route direction of the traveling road, means for measuring a steering angle that is a steering direction of a steering wheel provided in the vehicle, and And a vehicle attitude detection system for detecting attitude when the degree of coincidence is equal to or greater than a predetermined threshold.

Images